The $4.99 chicken deal was so important to the Issaquah-based warehouse retailer that it took at least a $30 million profit hit to subsidize the product during a 2015 bird flu outbreak.

Costco beats the competition with bigger birds, bigger ovens and less expensive packaging. The next step is a chicken processing plant that will cost about $300 million and supply Costco at a lower price than suppliers offer.

Costco said it sold 87 million rotisserie chickens last year. The new plant will process about 100 million birds per year, or about a quarter of Costco’s annual appetite, Chief Financial Officer Richard Galanti said on an earnings call in October.

Costco also has two plants run by well-known but unnamed suppliers (one of which is likely Pilgrim’s Pride) that it retrofitted for higher efficiency, Galanti said.

“Guess what: if you are to greatly reduce the SKUs, you make the manufacturing more efficient, you can save — given the week and given what happens with all the byproduct and the markets themselves — we can guarantee sourcing and lower our costs by anywhere from 10 cents to 35 cents a bird,” he said.